A New Aspect of Predator–Prey Dynamics: The Case of a Livestock Guardian Dog Predating upon an Invasive Coypu in Lake Kerkini, Greece

Abstract

Invasive alien species frequently encounter limited natural predation pressure in their non-native ranges, which can contribute significantly to their unchecked proliferation and adverse ecological impacts. Here, we document a novel instance of a livestock guardian dog preying upon an adult coypu (Myocastor coypus) in Lake Kerkini, Greece—a significant observation given the coypu’s status as a prominent invasive species with few natural predators in Europe. The coypu’s presence in the region, coupled with the absence of effective predation among others, has allowed it to establish a robust population and exert considerable pressure on local ecosystems. This novel observation not only highlights an unusual predator–prey interaction involving a domestic mammal traditionally used for livestock management but also provides insights into understanding how domestic animals might inadvertently influence the dynamics of invasive species, potentially serving as a complementary tool in conservation management. By demonstrating that domestic dogs could play a role in controlling invasive species populations, our findings introduce a previously unconsidered aspect of invasive species management with conservation implications.

1. Introduction

Invasive alien species (IAS) have emerged as a pressing global challenge, impacting ecosystems, biodiversity, and human well-being [1,2,3], with recent studies indicating a dramatic 40% increase in the introduction of these species over the past four decades [4]. The repercussions of these invasions are far-reaching, often leading to the restructuring of ecosystems, disruption of ecological balances, and alteration of fundamental environmental processes [5]. In parallel, IAS pose a direct threat to vital ecosystem services and can drive native species toward endangerment or even extinction through mechanisms such as predation, competition, hybridization, and the spread of pathogens [6,7].

Among these IAS, the coypu or nutria, Myocastor coypus (Molinia 1782), a large semi-aquatic rodent originally from South America, has recently gained attention as a particularly invasive species. It belongs to the family Myocastoridae within the order Rodentia, specifically classified in the suborder Hystricomorpha. Adult coypus typically weigh between 5 and 10 kg and can measure up to 60 cm in body length, with an additional tail length of approximately 30 cm. They exhibit a robust, cylindrical body covered with dense, waterproof fur that ranges in color from brown to gray, with a lighter underside. Their webbed feet make them agile swimmers, and they have large, orange incisors that enable them to feed on a variety of plant materials, including aquatic vegetation and crops [8]. The coypu’s remarkable adaptability and effective dispersal capabilities have facilitated its spread across diverse habitats, while its ability to thrive in various environments and consume a wide range of food sources significantly enhances its invasive potential [8,9]. This adaptability has led to substantial ecological consequences, including the disruption of plant communities, alterations in native vegetation dynamics [10], and negative impacts on avian populations [11,12], resulting in its inclusion on the list of the “100 of the World’s Worst Invasive Alien Species” [13]. Additionally, coypu also acts as a potential reservoir for leptospirosis, a public health concern in Europe [14,15].

In parallel, the coypu’s adaptability is not solely limited to its habitat and diet; it also reflects the dynamics of its interactions with predators. In its native range, the coypu is preyed upon by a variety of predators, including jaguars (Panthera onca), pumas (Puma concolor), ocelots (Leopardus pardalis), oncillas (Leopardus tigrinus), mountain lions (Felis concolor), and gray foxes (Lycalopex spp.), as well as various reptiles like caimans (Caiman longirostris, C. sclerops, and C. niger) [16,17,18].

In Europe, however, the predator spectrum is less diverse. This, in combination with the coypu’s high reproductive potential [19,20,21], facilitates its rapid population growth [22] following escapes or deliberate releases [23]. Although some predators, such as the red fox (Vulpes vulpes) and the common buzzard (Buteo buteo) in France, as well as the red fox and grey wolf (Canis lupus) in Italy [24,25], have been reported to prey on coypu, much of this information comes from anecdotal reports or studies lacking direct observational evidence.

Similarly, in Greece, a global biodiversity hotspot [26,27], the increasing presence of IAS like the coypu poses a significant threat to the country’s ecosystems and species. Although the coypu has been present in the country for nearly six decades [28], its ecological impact—amplified by the lack of natural predators—has not yet been fully recognized [28,29]. This mirrors the broader European scenario, where the scarcity of natural predators has facilitated the rapid expansion of coypu populations, leading to widespread environmental disruption.

In light of these concerns, here, we present the first photographic evidence from the National Park of Lake Kerkini, Greece, documenting a predation event: a domestic mammal preyed upon an adult coypu. We also discuss the potential ecological implications of this event and the role of domestic animals in managing invasive species.

2. Materials and Methods

2.1. Study Area

The National Park of Lake Kerkini, located in Northern Greece near the Greek–Bulgarian border, is characterized by a mosaic of habitats, including forests, wetlands, grasslands, and agricultural areas. The lake and its surrounding wetlands support a wide variety of riparian habitats, including open water, marshes, reed beds, and patches of riparian forest, while they have been designated as a Ramsar Wetland and are part of the Natura 2000 network. These diverse habitats provide sanctuary to numerous species of flora and fauna, making the area a significant biodiversity hotspot in Greece.

Lake Kerkini’s surrounding landscape is also characterized by human activities, including agriculture and livestock grazing, which influence the ecological dynamics of the region. Over 6000 water buffaloes (Bubalus bubalis), which are integral to Greek livestock farming [30], move freely across the area. These buffaloes are primarily managed and protected by livestock guardian dogs (pers. obs.), which are left unsupervised to accompany the herds as they daily roam freely over large distances and contribute to the shaping of the area through their grazing patterns and interactions with the ecosystem (Figure 1).

The study area experiences a climate that falls between continental and Mediterranean, characterized by hot, dry summers and mild, humid winters. This climate type is classified as intense medium-Mediterranean with an average annual temperature of 12.6 °C and an annual precipitation of 569 mm [31].

2.2. Monitoring and Documentation of the Predation Event

As part of our ongoing research, which focuses on recording the presence and behavior of coypus as well as their interactions with other species, we have conducted extensive monitoring across various areas of Lake Kerkini National Park.

During these surveys, we observed and documented a significant predation event of a domestic mammal preying upon an adult coypu. The event was recorded using binoculars and a camera equipped with a telephoto lens to ensure clear and detailed imagery. We noted the date, time, and precise location of the encounter, and species identification was confirmed based on visual observations of morphological characteristics. All observed behaviors were documented, including the initial response of the preyed individual to the perceived threat, its escape attempts, the tactics employed by the domestic mammal during the predation, and the subsequent process of predation.

3. Results

On 20 January 2023, at 16:55 h (local time), while conducting routine monitoring near Lake Kerkini, we observed rapid movement along the water’s edge from an open field approximately 500 m away. As we approached the locality of the event, we determined that it involved a water buffalo livestock guardian dog (estimated weight: >40 kg) engaged in a predatory encounter with an adult coypu (41°14′53.8″ N 23°12′15.0″ E; Figure 2). Weather conditions at the time were sunny with an ambient temperature of 8 °C, just before sunset.

Initially, the dog was positioned more than 50 m away from a coypu, near a buffalo herd. Upon spotting the coypu, the dog began running at high speed towards the coypu. Within seconds, it had closed the distance and engaged in a direct confrontation with the unsuspecting coypu, who appeared startled and initially unaware of the impending threat.

The livestock guardian dog executed a swift and precise attack, closing the distance with remarkable agility and seizing the coypu’s neck with its jaws. The coypu began to shake and made circular movements with its body in an attempt to free itself from the dog’s grasp. Despite these efforts, the dog maintained a firm grip on the coypu’s neck and employed a lethal technique, using vigorous shaking and twisting to break the coypu’s neck.

This efficient killing method subdued the coypu within less than two minutes. Once the coypu was dead, the dog began to consume it. Observing from approximately 50 m away, we noted that the dog continued to feed on the carcass without showing any concern for our presence. The feeding process was thorough, with the dog consuming various parts of the prey (Figure 3). Over the course of the observation, the dog methodically consumed nearly the entire coypu, leaving behind only minimal remains.

4. Discussion

In this study, we present the first documented instance of a livestock guardian dog successfully preying upon and consuming an adult coypu—a novel observation with significant implications. This finding is particularly noteworthy as it provides verifiable evidence that livestock guardian dogs, traditionally employed for livestock management, can occasionally function as opportunistic predators of coypu—a species that, in its non-native range, is generally considered to face limited predation pressure. While predation by domestic dogs on coypu, alongside other mammalian predators such as golden jackals (Canis aureus), gray wolves (Canis lupus), the jungle cat (Felis chaus), has been mentioned anecdotally in older literature reports from regions outside Europe, such as Georgia and Azerbaijan [32], our documentation provides new, verifiable evidence of such behavior and raises new questions about the role of domestic animals in the management of invasive species.

The conservation implications of this finding extend beyond merely documenting a predation event. It invites a broader consideration of the potential role that domestic animals, particularly livestock guardian dogs, might play in interacting with invasive species like the Coypu. Domestic animals are often overlooked in discussions of wildlife management, yet their interactions with local fauna can be significant. For example, domestic cats have been documented as predators of different taxa of reptiles and amphibians [33,34], invertebrates [35], birds [36,37], and small mammals [38,39]. Similarly, free-ranging chickens have been known to impact invertebrate communities and reptiles in rural areas [40].

In agricultural and pastoral areas, such as in our case, dogs have been primarily used to manage livestock, but their influence can extend to shaping wildlife populations through predation or competitive exclusion [41]. As natural predators, dogs have the instinctual capacity to prey upon a wide range of species [42], including ungulates [43], small mammals [44,45], reptiles and amphibians [46], and birds [47]. Beyond direct predation, their presence can lead to harassment or chasing of native species, causing increased stress and energy expenditure in the affected wildlife [48]. Dogs can also serve as intraguild competitors, affecting the distribution and behavior of other carnivores [41].

The role of livestock guardian dogs as incidental predators may warrant further exploration in the context of invasive species management, particularly in regions where they are already an integral part of the landscape. However, their dietary habits are a critical factor in understanding their actual ecological impact [49]. Further research is required to determine whether Coypu predation forms a consistent part of their diet or if it is an incidental occurrence. Without such dietary analysis, it remains challenging to quantify the potential role of these dogs in regulating Coypu populations.

The dog observed in this study belongs to a lupoid pastoral type, characterized by wolf-like features such as a strong, muscular build, erect ears, and a dense coat, traits which enhance its endurance and ability to guard livestock over large areas. These dogs are commonly associated with water buffalo herds in the Lake Kerkini region. Historically, similar lupoid pastoral dogs have been documented, by Von Stephanitz [50], tending to water buffalo and cattle herds in southern Macedonia, particularly between Gevgelija and Doirani Lake. These dogs’ strong predatory instincts and protective behavior towards livestock may naturally extend to preying upon invasive species like the coypu, suggesting that their role in local ecosystems could be more complex than previously understood.

This complexity is further highlighted by the specific environmental conditions at Lake Kerkini, which provide an ideal habitat for the coypu. The lake, with its diverse habitats and abundant food resources, supports the proliferation of this invasive species. Coypu has been observed in various parts of the National Park, including wetlands, agricultural areas, and along the shores of the lake. The combination of aquatic and riparian habitats, along with minimal predation pressure, creates favorable conditions for their continued spread. Although specific population estimates in the area are lacking, our observations over the past four years suggest that more than 150 individuals currently inhabit the region, marking it as a significant invasion hotspot.

Despite the presence of several potential predators in Lake Kerkini, including the red fox, golden jackals, grey wolf, and various birds of prey, predation pressure on coypus appears to be insufficient to effectively control their population. This gap in natural predation creates favorable conditions for the continued spread of coypu across the area. However, the extent to which livestock guardian dogs could impact coypu population dynamics remains unclear. The observed predation by livestock guardian dogs on coypu introduces a potential natural control mechanism that could mitigate the population growth of this invasive species. However, while this may seem like a beneficial intervention, there is a need to carefully evaluate whether this behavior extends to native species in the area. The unsupervised roaming of dogs may lead to unintended negative impacts on local fauna, contributing to declines in certain native species or disrupting ecosystem dynamics.

By deepening our understanding of these dynamics, we can better assess the role of domestic animals in shaping the populations of invasive species. This knowledge could contribute to more effective conservation practices, ensuring that the ecological balance is maintained while addressing the challenges posed by invasive species.